ioctl_syscall updates

src/safeposix/syscalls/fs_calls.rs

@@ -2042,38 +2042,76 @@ impl Cage {
     }
 
     //------------------------------------IOCTL SYSCALL------------------------------------
+    //Description
+    //ioctl manipulates the underlying device parameters of special files. In particular, it is used as a way
+    //for user-space applications to interface with device drivers. 
+
+    //Function arguments
+    //The function accepts three arguments:
+    //1. fd       - an open file descriptor that refers to a device.
+    //2. request  - the control function to be performed. The set of valid request values depends entirely on the device
+    //              being addressed. MEDIA_IOC_DEVICE_INFO is an example of an ioctl control function to query device
+    //              information that all media devices must support.
+    //3. ptrunion - additional information needed by the addressed device to perform the selected control function.
+    //              In the example of MEDIA_IOC_DEVICE_INFO request, a valid ptrunion value is a pointer to a struct 
+    //              media_device_info, from which the device information is obtained.
+
+    //Return values
+    //Upon successful completion, a value other than -1 that depends on the selected control function is returned.
+    //In case of a failure, -1 is returned with errno set to a particular value, like EBADF, EINVAL, etc.
+
+    //To learn more about the syscall, control functions applicable to all the devices, and possible error values,
+    //see https://man.openbsd.org/ioctl
 
     pub fn ioctl_syscall(&self, fd: i32, request: u32, ptrunion: IoctlPtrUnion) -> i32 {
+        //BUG
+        //if the provided file descriptor is out of bounds, 'get_filedescriptor' returns Err(),
+        //unwrapping on which  produces a 'panic!'
+        //otherwise, file descriptor table entry is stored in 'checkedfd'
         let checkedfd = self.get_filedescriptor(fd).unwrap();
         let mut unlocked_fd = checkedfd.write();
+        //if a table descriptor entry is non-empty, a valid request is performed
         if let Some(filedesc_enum) = &mut *unlocked_fd {
+            //For now, the only implemented control function is FIONBIO command used with sockets 
             match request {
+                //for FIONBIO, 'ptrunion' stores a pointer to an integer. If the integer is 0, the socket's
+                //nonblocking I/O is cleared. Otherwise, the socket is set for nonblocking I/O
                 FIONBIO => {
+                    //if 'ptrunion' stores a Null pointer, a 'Bad address' error is returned
+                    //otheriwse, the integer value stored in that address is returned and saved into 'arg_result'
                     let arg_result = interface::get_ioctl_int(ptrunion);
-                    //matching the tuple and passing in filedesc_enum
                     match (arg_result, filedesc_enum) {
                         (Err(arg_result), ..)=> {
-                            return arg_result; //syscall_error
+                            return arg_result;
                         }
+                        //since FIONBIO command is used with sockets, we need to make sure that the provided
+                        //file descriptor addresses a socket
+                        //otherwise, a 'Not a typewriter' error designating that the specified command
+                        //is only applicable to sockets is returned 
                         (Ok(arg_result), Socket(ref mut sockfdobj)) => {
                             let sock_tmp = sockfdobj.handle.clone();
                             let mut sockhandle = sock_tmp.write();
-
                             let flags = &mut sockfdobj.flags;
                             let arg: i32 = arg_result;
                             let mut ioctlret = 0;
-
-                            if arg == 0 { //clear non-blocking I/O
+                            //clearing nonblocking I/O on the socket if the integer is 0
+                            if arg == 0 { 
                                 *flags &= !O_NONBLOCK;
+                                //libc::fcntl is called under the hood with F_SETFL command and 0 as an argument
+                                //to set blocking I/O, and the result of the call is stored in ioctlret
                                 if let Some(ins) = &mut sockhandle.innersocket {
+
                                     ioctlret = ins.set_blocking();
                                 }
-                            } else { //set for non-blocking I/O
+                            } else {
                                 *flags |= O_NONBLOCK;
+                                //libc::fcntl is called under the hood with F_SETFL command ans O_NONBLOCK as an argument
+                                //to set nonblocking I/O, and the result of the call is stored in ioctlret
                                 if let Some(ins) = &mut sockhandle.innersocket {
                                     ioctlret = ins.set_nonblocking();
                                 }
                             }
+                            //if ioctlret is negative, it means that the call to fcntl returned with an error
                             if ioctlret < 0 {
                                 match Errno::from_discriminant(interface::get_errno()) {
                                     Ok(i) => {return syscall_error(i, "ioctl", "The libc call to ioctl failed!");},

src/tests/fs_tests.rs

@@ -23,7 +23,8 @@ pub mod fs_tests {
         ut_lind_fs_fcntl_valid_args();
         ut_lind_fs_fcntl_invalid_args();
         ut_lind_fs_fcntl_dup();
-        ut_lind_fs_ioctl();
+        ut_lind_fs_ioctl_valid_args();
+        ut_lind_fs_ioctl_invalid_args();
         ut_lind_fs_fdflags();
         ut_lind_fs_file_link_unlink();
         ut_lind_fs_file_lseek_past_end();
@@ -525,48 +526,75 @@ pub mod fs_tests {
     }
 
 
-    pub fn ut_lind_fs_ioctl() {
+    pub fn ut_lind_fs_ioctl_valid_args() {
         lindrustinit(0);
         let cage = interface::cagetable_getref(1);
 
+        //setting up two integer values (a zero value to test clearing nonblocking I/O behavior
+        //and a non-zero value to test setting nonblocking I/O behavior)
         let mut arg0: i32 = 0;
         let mut arg1: i32 = 1;
 
+        //ioctl requires a pointer to an integer to be passed with FIONBIO command
         let union0: IoctlPtrUnion = IoctlPtrUnion { int_ptr: &mut arg0 };
         let union1: IoctlPtrUnion = IoctlPtrUnion { int_ptr: &mut arg1 };
 
         let sockfd = cage.socket_syscall(AF_INET, SOCK_STREAM, 0);
-        let filefd = cage.open_syscall("/ioctl_file", O_CREAT | O_EXCL, S_IRWXA);
-
-        //try to use FIONBIO for a non-socket
-        assert_eq!(
-            cage.ioctl_syscall(filefd, FIONBIO, union0),
-            -(Errno::ENOTTY as i32)
-        );
 
-        //clear the O_NONBLOCK flag
+        //calling ioctl with FIONBIO command and a pointer to a zero-valued integer
+        //to clear the socket's nonblocking I/O, and checking if the flag was correctly set 
         assert_eq!(cage.ioctl_syscall(sockfd, FIONBIO, union0), 0);
-
-        //checking to see if the flag was updated
         assert_eq!(cage.fcntl_syscall(sockfd, F_GETFL, 0) & O_NONBLOCK, 0);
 
-        //set the O_NONBLOCK flag
+        //calling ioctl with FIONBIO command and a pointer to a non-zero-valued integer
+        //to set the socket's nonblocking I/O, and checking if the flag was correctly set
         assert_eq!(cage.ioctl_syscall(sockfd, FIONBIO, union1), 0);
+        assert_eq!(cage.fcntl_syscall(sockfd, F_GETFL, 0) & O_NONBLOCK, O_NONBLOCK);
 
-        //checking to see if the flag was updated
-        assert_eq!(
-            cage.fcntl_syscall(sockfd, F_GETFL, 0) & O_NONBLOCK,
-            O_NONBLOCK
-        );
+        assert_eq!(cage.close_syscall(sockfd), 0);
 
-        //clear the O_NONBLOCK flag
-        assert_eq!(cage.ioctl_syscall(sockfd, FIONBIO, union0), 0);
+        assert_eq!(cage.exit_syscall(EXIT_SUCCESS), EXIT_SUCCESS);
+        lindrustfinalize();
+    }
 
-        //checking to see if the flag was updated
-        assert_eq!(cage.fcntl_syscall(sockfd, F_GETFL, 0) & O_NONBLOCK, 0);
+    pub fn ut_lind_fs_ioctl_invalid_args() {
+        lindrustinit(0);
+        let cage = interface::cagetable_getref(1);
+
+        //setting up two integer values (a zero value to test clearing nonblocking I/O behavior on
+        //non-socket type and a non-zero value to test setting nonblocking I/O behavior 
+        //on non-socket type)
+        let mut arg0: i32 = 0;
+        let mut arg1: i32 = 1;
+
+        //ioctl requires a pointer to an integer to be passed with FIONBIO command
+        let union0: IoctlPtrUnion = IoctlPtrUnion { int_ptr: &mut arg0 };
+        let union1: IoctlPtrUnion = IoctlPtrUnion { int_ptr: &mut arg1 };
 
+        let sockfd = cage.socket_syscall(AF_INET, SOCK_STREAM, 0);
+        let filefd = cage.open_syscall("/ioctl_file", O_CREAT | O_EXCL, S_IRWXA);
+
+        //trying to use FIONBIO command on a non-socket type (the file type in this case) 
+        //for any 'ptrunion' value should throw a 'Not a typewriter' error
+        assert_eq!(cage.ioctl_syscall(filefd, FIONBIO, union0), -(Errno::ENOTTY as i32));
+        assert_eq!(cage.ioctl_syscall(filefd, FIONBIO, union1), -(Errno::ENOTTY as i32));
         assert_eq!(cage.close_syscall(filefd), 0);
+
+        //calling 'ioctl' with a control function that is not implemented yet should
+        //return an 'Invalid argument' error
+        //21600 is an arbitrary integer that does not correspond to any implemented
+        //control functions for ioctl syscall
+        assert_eq!(cage.ioctl_syscall(sockfd, 21600, union0), -(Errno::EINVAL as i32));
+
+        //calling ioctl with FIONBIO command and a null pointer 
+        //should return a 'Bad address' error
+        let null_ptr: *mut i32 = std::ptr::null_mut();
+        let union_null: IoctlPtrUnion = IoctlPtrUnion { int_ptr: null_ptr };
+        assert_eq!(cage.ioctl_syscall(sockfd, FIONBIO, union_null),-(Errno::EFAULT as i32));
+
+        //calling ioctl on a closed file descriptor should throw a 'Bad file number' error
         assert_eq!(cage.close_syscall(sockfd), 0);
+        assert_eq!(cage.fcntl_syscall(sockfd, F_GETFL, 0), -(Errno::EBADF as i32));
 
         assert_eq!(cage.exit_syscall(EXIT_SUCCESS), EXIT_SUCCESS);
         lindrustfinalize();